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Biomedical subjects

D Roos

Publications and source records attributed to D Roos.

At least 127 records · Page 7Linked to original sources

Neutrophil Fc gamma RIIIb deficiency, nature, and clinical consequences: a study of 21 individuals from 14 families.

Several individuals have been described whose neutrophils lack the normally abundantly expressed IgG Fc gamma receptor IIIb (Fc gamma RIIIb). We now studied the responsible genomic defect and analyzed the medical history in detail of 21 Fc gamma RIIIb-negative donors identified in 14 unrelated families. We developed a polymerase chain reaction allele-specific-primer annealing assay to genotype for the NA polymorphism of the Fc gamma RIIIB gene. All Fc gamma RIIIb-deficient individuals were negative for both the NA1 and the NA2 allele. In all cases the complete absence of the Fc gamma RIIIB alleles was confirmed using a Southern blot-based restriction fragment length polymorphism assay. Furthermore, an additional deletion of the next more telomeric located Fc gamma RIIC gene was found. Family studies showed that at least one Fc gamma RIIIB allele was absent in both parents in 6 families, whereas in 2 families the father had a normal phenotype. Two individuals suffered from an autoimmune thyroiditis. Four individuals had had multiple episodes of infection, 3 had only incidental infections, and 14 never had any serious infection. Genotyping showed a normal Fc gamma RIIa phenotype distribution among the Fc gamma RIIIb-negative individuals, thus excluding the possibility that the presence of the favorable IgG2-binding low-responder isoform of Fc gamma RIIa (131-H) contributed to the overall absence of recurrent bacterial infections.

Adolescent↗

Interactions between the cytosolic components p47phox and p67phox of the human neutrophil NADPH oxidase that are not required for activation in the cell-free system.

Activation of the human NADPH oxidase requires the interaction of at least four cytosolic proteins and one membrane-bound heterodimeric protein. Src homology 3 (SH3) domains and their proline-rich counterstructures have been shown to play an important role in protein-protein interactions. Because it was found that the cytosolic oxidase components p67phox, p47phox, and p40phox reside in a complex in resting neutrophils, we studied the role of SH3 domains in their interaction by use of an overlay technique. Wild-type and mutated 35S-labeled p67phox and p47phox were used to detect immobilized cytosolic proteins on a protein blot. A specific association of native p67phox to blotted p47phox and blotted p40phox was found. These interactions were not disturbed by deleting the only proline-rich region (amino acids 227-231) in p67phox. We also found a specific association of native p47phox with blotted p67phox. Deletions in a putative SH3-binding region of p47phox completely abrogated the interaction with p67phox. Other results suggest that the C terminus of p47phox exposes this SH3-binding domain for interaction with p67phox. Similar results were obtained when the binding of cytosolic p67phox to wild-type or mutated p47phox were studied in solution. Interestingly, mutants of p47phox unable to bind to p67phox were fully capable of supporting superoxide production under cell-free activation conditions. We conclude that an interaction between the C-terminal proline-rich region of p47phox and the second SH3 domain of p67phox is not required for oxidase activity in the cell-free assay.

Base Sequence↗

Heterotypic Fc gamma R clusters evoke a synergistic Ca2+ response in human neutrophils.

Both Fc gamma receptors on human neutrophils (Fc gamma RIIa and Fc gamma RIIIb) are capable of initiating signal transduction after multivalent cross-linking. However, immune complexes most likely activate neutrophils by a combined homotypic and heterotypic cross-linking of Fc gamma Rs. We have investigated the effect of homotypic and heterotypic Fc gamma R cluster formation on changes in the intracellular free Ca2+ concentration. Combined heterotypic and homotypic cluster formation resulted in a Ca2+ response that was strongly enhanced as compared to the sum of both individual Fc gamma R responses. This synergistic response was caused by the formation of heterotypic clusters of Fc gamma Rs and not by the simultaneous formation of homotypic clusters. This conclusion was supported by experiments with a bispecific antibody binding to both Fc gamma RIIa and Fc gamma RIIIb. The heterotypic Fc gamma R cross-linking results in efficient activation of Ca2+ influx, probably caused by a more pronounced depletion of intracellular Ca2+ stores. Stimulation with immune complexes also induced Ca2+ influx in normal neutrophils, but not in Fc gamma RIIIb-deficient neutrophils. The synergism between both Fc gamma Rs was also apparent in other responses of neutrophils, such as the activation of the respiratory burst. This study shows that the two different Fc gamma Rs on neutrophils complement each other in mediating an important cellular response.

Antibodies, Monoclonal↗

Eosinophils isolated with two different methods show different characteristics of activation.

Eosinophils can be isolated from a mixed suspension of granulocytes by different procedures. We compared functional responses of human eosinophils purified according to two different principles: (1) an fMLP-induced difference in specific gravity between eosinophils and neutrophils and (2) selective removal of neutrophils by means of immunomagnetic beads coated with CD16 mAb. The results showed that eosinophils isolated with the CD16 beads method have a higher capacity to synthesize platelet activating factor (PAF) after stimulation with serum-treated zymosan (STZ) than eosinophils purified with the fMLP method. Binding of STZ and subsequent activation of the respiratory burst were also increased in CD16-isolated eosinophils. Furthermore, eosinophils isolated with the CD16 beads showed stronger chemotactic responses towards C5a and PAF. The difference in activity of these eosinophil preparations might be explained by a loss of the more active cells during the isolation with the fMLP method: only 30-60% of the eosinophils were recovered with this method, in contrast to a recovery of more than 95% with the CD16 beads method. Indeed, this 'lost' population of eosinophils, subsequently purified with CD16-coated beads, had a higher respiratory burst activity. The alternative explanation, i.e., an enhancement of eosinophil function by the beads method, appeared not to be valid, because repurification of fMLP-isolated eosinophils in the presence of fresh neutrophils and CD16-coated beads did not change the reactivity of the eosinophils. We conclude that the fMLP method leads to selective purification of eosinophils with a resting (or 'unprimed') phenotype.

Antigens, CD↗

Human neutrophils lose their surface Fc gamma RIII and acquire Annexin V binding sites during apoptosis in vitro.

We have previously reported that neutrophilic granulocytes rapidly release part of their Fc gamma RIII from the plasma membrane upon in vitro activation, probably by proteolytic cleavage. In plasma and other body fluids, released or soluble Fc gamma RIII has been found in considerable amounts. In the present study, neutrophils were kept in maintenance culture for 18 to 24 hours. Forty percent of the neutrophils completely lost Fc gamma RIII, and the remainder of the cells showed a 60% decrease in Fc gamma RIII expression on their surface. Released Fc gamma RIII was detected in the culture supernatant. Nevertheless, more than 90% of the cells was viable as judged by hydrolysis of fluorescein diacetate. The presence of interferon gamma, granulocyte colony-stimulating factor, or granulocyte-macrophage colony-stimulating factor, but not interleukin-3 (IL-3), IL-6, or IL-8, in the culture medium increased the number of cells that still expressed Fc gamma RIII. We found that this loss of Fc gamma RIII was not the result of cell activation but correlated strongly with apoptosis. The Fc gamma RIII-negative subpopulation exhibited typical morphologic changes, such as nuclear condensation and DNA fragmentation. Furthermore, this subpopulation appeared to have acquired the property of binding Annexin V, a calcium-dependent, phospholipid-binding protein with high affinity for phosphatidylserine. The external exposure of this phospholipid by cells has been reported to occur during apoptosis. The property of Annexin V binding was not shared by the nonapoptotic, Fc gamma RIII-positive subpopulation. In this respect, we identified binding of Annexin V as an convenient marker for apoptotic cells. Our results indicate that soluble Fc gamma RIII in body fluids might be derived for a large part from neutrophils undergoing apoptosis in the tissues.

Annexin A5↗

Prevalence, genetics and clinical presentation of chronic granulomatous disease in Sweden.

To estimate the prevalence of chronic granulomatous disease (CGD) in Sweden, an inquiry asking for known and possible CGD cases was mailed to paediatric, internal medicine and infectious disease departments all over Sweden. The detected patients were characterized as to genetics and the clinical presentation. Twenty-one patients (belonging to 16 different families) were found, corresponding to a prevalence of approximately 1/450,000 individuals. The patients with X-linked disease, lacking a functional gp91phox protein (n = 12), comprised 57% and 43% of the patients had an autosomal recessive (AR) disease lacking p47phox (n = 7) or p67phox (n = 1), respectively. All unrelated patients with X-linked disease displayed different gene abnormalities such as point mutations predicting nonsense (n = 3), missense (n = 1) or splice site mutations (n = 2), but also a total deletion and a unique 40 base pair duplicature insertion. The patients with p47phox-deficiency showed a GT deletion at a GTGT tandem repeat, and the p67phox-deficient patient displayed a heterozygous in-frame deletion of AAG combined with a large deletion in the other allele. Three patients died during the study period, two from pseudomonas cepacia infections. Patients with X-linked disease had more frequent infections (mean of 1.7 per year), than the patients with AR inheritance (0.5 infections per year). The most common infections were dermal abscesses (n = 111), followed by lymphadenitis (n = 82) and pneumonias (n = 73). Inflammatory bowel disease-like symptoms, mimicking Crohn's disease of the colon, was seen in three CGD patients.

Adolescent↗

Polarized secretion of interleukin-8 by human mesothelial cells: a role in neutrophil migration.

We investigated the role of human mesothelium in an in vitro model of peritonitis with emphasis on the secretion of the neutrophil chemoattractant interleukin-8 (IL-8) and the migration of polymorphonuclear leucocytes (PMN) across monolayers of peritoneal mesothelial cells. PMN showed minimal migration across non-activated mesothelial monolayers (< 2%). However, migration was induced after mesothelial cell activation by IL-1 beta (24%) and this induced migration was significantly blocked by antibodies against IL-8 (63% inhibition; P < or = 0.01). IL-1 beta-activated mesothelial monolayers were shown to secrete IL-8 in a polarized way, which was preferentially oriented towards the apical side of the monolayer. Our results indicate that the influx of PMN into the peritoneal cavity is, at least in part, controlled by the mesothelial cell layer of the peritoneal membrane.

Cell Movement↗

156Pro-->Gln substitution in the light chain of cytochrome b558 of the human NADPH oxidase (p22-phox) leads to defective translocation of the cytosolic proteins p47-phox and p67-phox.

Src homology 3 (SH3) domains have been suggested to play an important role in the assembly of the superoxide-forming nicotinamide adenine dinucleotide phosphate (NADPH) oxidase upon activation of phagocytes, which involves the association of membrane-bound and cytosolic components. We studied the translocation of the cytosolic proteins to the plasma membrane in neutrophils of a patient with a point mutation in the gene encoding the light chain of cytochrome b558. This mutation leads to a substitution at residue 156 of a proline into a glutamine in a putative SH3 binding domain of p22-phox (Dinauer, M., E. A. Pierce, R. W. Erickson, T. Muhlebach, H. Messner, R. A. Seger, S. H. Orkin, and J. T. Curnutte. 1991. Proc. Natl. Acad. Sci. 88:11231). In PMA-stimulated neutrophils and in a cell-free translocation assay with neutrophil membranes and cytosol, association of the cytosolic proteins p47-phox and p67-phox with the membrane fraction of the patient's neutrophils was virtually absent. In contrast, when solubilized membranes of the patient's neutrophils were activated with phospholipids in the absence of cytosol (Koshkin, V., and E. Pick. 1993. FEBS [Fed. Eur. Biochem. Soc.] Lett. 327:57), the rate of NADPH-dependent oxygen uptake was observed at a rate similar to that of control membranes. We suggest that the binding of an SH3 domain of p47-phox to p22-phox, and thus activation of the oxidase, does not occur in the neutrophils of this patient, although under artificial conditions, electron flow from NADPH to oxygen in cytochrome b558 is possible.

Blotting, Western↗

Granulocyte colony-stimulating factor administration to healthy volunteers: analysis of the immediate activating effects on circulating neutrophils.

In four healthy volunteers, we analyzed in detail the immediate in vivo effects on circulating neutrophils of subcutaneous administration of 300 micrograms of granulocyte colony-stimulating factor (G-CSF). Neutrophil activation was assessed by measurement of degranulation. Mobilization of secretory vesicles was shown by a decrease in leukocyte alkaline phosphatase content of the circulating neutrophils. Furthermore, shortly postinjection, Fc gamma RIII was found to be upregulated from an intracellular pool that we identified by immunoelectron microscopy as secretory vesicles. Intravascular release of specific granules was shown by increased plasma levels of lactoferrin and by upregulation of the expression of CD66b and CD11b on circulating neutrophils. Moreover, measurement of fourfold elevated plasma levels of elastase, bound to its physiologic inhibitor alpha 1-antitrypsin, indicated mobilization of azurophil granules. However, no expression of CD63, a marker of azurophil granules, was observed on circulating neutrophils. G-CSF--induced mobilization of secretory vesicles and specific granules could be mimicked in whole blood cultures in vitro, in contrast to release of azurophil granules. Therefore, we postulate that the most activated neutrophils leave the circulation, as observed shortly postinjection, and undergo subsequent stimulation in the endothelial microenvironment, resulting in mobilization of azurophil granules. Our data demonstrate that G-CSF should be regarded as a potent immediate activator of neutrophils in vivo.

Adult↗

[Molecular-genetic studies of carrier stage of glucose-6-phosphate dehydrogenase deficiency].

OBJECTIVE: Determining the reliability of a new DNA analysis in the detection of carriers of 6 mutations that cause glucose-6-phosphate dehydrogenase (G6PD) deficiency. DESIGN: Validation of a diagnostic test. SETTING: Central Laboratory of the Netherlands Red Cross Blood Transfusion Service in Amsterdam, the Netherlands. METHOD: With polymerase chain reactions (PCR) and restriction enzyme analyses, the DNA of 78 proven patients or carriers was compared with the DNA of 51 patients suffering from haemolytic anaemia (possibly due to G6PD deficiency) and of 50 healthy blood donors. RESULTS: In 60 of the 78 patients, 1 or 2 of the 6 mutations were found that lead--according to the literature--to G6PD deficiency. In 2 of the 51 anaemic patients a clinically relevant mutation was found, while such a mutation was revealed in 3 of the 50 blood donors. All 3 had been born in Curaçao or Surinam, areas with a higher incidence of G6PD deficiency than the Netherlands. CONCLUSION: In comparison with G6PD activity tests, which leave 50% of carriers undetected, the described PCR method is a reliable test. Because G6PD activity measurement is independent of mutation analysis, we conclude that a combination of these tests will detect carriers of G6PD deficiency with a higher sensitivity than either of these tests separately.

Amino Acid Sequence↗

Cytokine-activated endothelial cells internalize E-selectin into a lysosomal compartment of vesiculotubular shape. A tubulin-driven process.

The fate of E-selectin expressed on TNF-activated monolayers of HUVEC was investigated by confocal laser scanning microscopy. Cytokine-activated endothelial cells internalized mAb to E-selectin in a very rapid, energy-dependent fashion. By contrast, mAb against ICAM-1 and VCAM-1 remained surface bound. The E-selectin mAb was recovered in intracellular compartments with a tubular morphology, some of which appeared to be interconnected. Cathepsin B, a ubiquitously expressed lysosomal protease, was found to co-localize in these structures. Functional specificity of E-selectin-internalization was observed upon addition of the fluorescent SLex-oligosaccharide to the activated HUVEC monolayers. Uptake into the same E-selectin-positive compartments was observed, whereas the control oligosaccharide Lex was not internalized at all. The process of internalization was found to be unaffected by most inhibitors of protein kinase C, cAMP-dependent PKA, or protein tyrosine kinase activity. Whereas cytochalasin B preincubation of HUVEC failed to inhibit the internalization process, colchicine and vinblastine, reagents that interfere with the metabolism of tubulin, prevented the formation of the elongated structures in which E-selectin would normally be internalized. Concomitantly, the expression of E-selectin at the cell surface was significantly increased.

Cell Adhesion Molecules↗

Granulocyte-macrophage colony-stimulating factor, interleukin-3 (IL-3), and IL-5 greatly enhance the interaction of human eosinophils with opsonized particles by changing the affinity of complement receptor type 3.

Eosinophil functions can be modulated by several cytokines such as granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5. We have investigated the modulatory role of these cytokines on the interaction of human eosinophils with opsonized particles (serum-treated zymosan [STZ]). Addition of STZ to eosinophils isolated from the peripheral blood of normal human donors resulted in an interaction of the STZ particles with only 15% to 25% of the cells. Treatment of the eosinophils with GM-CSF, IL-3, or IL-5 strongly enhanced both the rate of particle binding and the percentage of eosinophils binding STZ. The effect of the cytokines is most likely mediated by a change in affinity of the complement receptor type 3 (CR3) on the eosinophils for the complement fragment iC3b on the STZ particles. This is indicated by the observation that (1) the effect of the cytokines on STZ binding was prevented by a monoclonal antibody against the iC3b-binding site on CR3 and (2) the enhanced binding was already apparent before upregulation of CR3 on the cell surface was observed. In a previous study, similar results were obtained with platelet-activating factor (PAF)-primed eosinophils. Because we found that the cytokines strongly enhanced the STZ-induced PAF synthesis, we investigated the role of both released PAF and cell-associated PAF in the priming phenomenon by the cytokines. Cytokine priming appeared to be largely independent of the synthesis of PAF.

Eosinophils↗

Soluble Fc gamma RIIIa is present in plasma and is derived from natural killer cells.

Fc gamma RIII (CD16), a receptor for complexed IgG, is encoded by two very homologous genes: Fc gamma RIIIA and Fc gamma RIIIB. NK cells and macrophages express Fc gamma RIIIa, whereas only neutrophils constitutively express Fc gamma RIIIb. In a previous study we found that soluble (s)Fc gamma RIII in plasma seemed to originate only from neutrophils. However, CD16 mAb, directed against different epitopes of Fc gamma RIII, precipitated a glycoprotein from plasma of homozygous Fc gamma RIIIB gene-deficient donors. This glycoprotein migrated in a similar way as did released Fc gamma RIIIa derived from NK cells, whereas Fc gamma RIIIa released by cultured monocytes migrated differently and appeared to be more heavily glycosylated on SDS-PAGE. After deglycosylation, the M(r) of the plasma sFc gamma RIIIa was similar to that of released Fc gamma RIIIa. Moreover, V8-protease maps were identical. Therefore, we conclude that sFc gamma RIIIa is also present in plasma and is derived from NK cells. Because sFc gamma RIII levels are hardly detectable in the plasma of most homozygous Fc gamma RIIIB gene-deficient donors, we suspect that the sFc gamma RIIIa level is negligible compared with the level of sFc gamma RIIIb in plasma of healthy donors. Two patients with an NK cell lymphocytosis had a high plasma level of sFc gamma RIIIaNK. Furthermore, high levels of sFc gamma RIIIaNK were found in plasma of two patients with rheumatoid arthritis. Thus, the level of sFc gamma RIIIaNK might reflect either an increase in circulating NK cells or an enhanced release of Fc gamma RIIIaNK in certain diseases. This study shows that an assay that discriminates between sFc gamma RIIIa and sFc gamma RIIIb is necessary for the interpretation of sFc gamma RIII levels in patients.

Glycoproteins↗

Autosomal recessive chronic granulomatous disease with absence of the 67-kD cytosolic NADPH oxidase component: identification of mutation and detection of carriers.

Chronic granulomatous disease (CGD) is characterized by the failure of phagocytic leukocytes to kill certain bacteria and fungi. This is caused by deficiencies in one of the components of NADPH oxidase, the enzyme in phagocytic leukocytes that generates superoxide. In a rare, autosomal recessive form of CGD, a 67-kD cytosolic component of NADPH oxidase (p67-phox) is missing. Until now, mutations in the gene coding for this protein have not been identified. We now report on a 10-year-old girl with lymph node and liver abscesses who was recognized as an A67(0) CGD patient by lack of NADPH oxidase activity in her granulocytes, a cytosolic defect in a cell-free oxidase system, and lack of immunoreactive material with an antiserum against the p67-phox protein. mRNA for this protein was present in normal amounts in her monocytes. This p67-phox mRNA was reverse-transcribed, and the coding region was amplified by polymerase chain reaction in six overlapping fragments and was sequenced. The patient appeared to be homozygous for a G-233-->A mutation, resulting in a nonconservative amino acid change (78Gly-->Glu). This mutation was also found in the genomic DNA of this patient but not in that of 38 normal donors. Both parents and a sister proved to be carriers of the disease, as deduced from the mutation in only one allele. The carrier state was also manifested by intermediate superoxide production by their intact granulocytes and in the cell-free system.

Amino Acid Sequence↗

Identification of allele-specific p22-phox mutations in a compound heterozygous patient with chronic granulomatous disease by mismatch PCR and restriction enzyme analysis.

A rare subgroup (approx. 5%) of all chronic granulomatous disease (CGD) patients suffers from mutations in the gene encoding the small p22-phox subunit of the flavocytochrome b558 heterodimer, the terminal redox component of the phagocyte NADPH oxidase. A male CGD patient with neutrophil granulocytes devoid of any spectrometrically detectable cytochrome b558 owing to autosomally inherited p22-phox deficiency (phenotype, A22-) is reported. The patient was identified as being compound heterozygous for two independent mutations of his p22-phox alleles. On the maternal allele a single base substitution (A186 to T) was found that predicts a nonconservative replacement of Glu 53 by Val. On his paternal p22-phox allele a G was found to be added to a G stretch between nucleotides G195 and G199 in the cDNA sequence. The resulting frame shift predicts an aberrant open reading frame, 16 amino acids longer than the normal p22-phox polypeptide. Genomic DNA was tested for the presence of the mutant allele by mismatch PCR (polymerase chain reaction). For this purpose, a single base mismatch was introduced at nucleotide position 189, leading to digestion of the normal allele by the restriction enzyme HinfI. The maternal allele was found to be present in 50% of the patient's DNA and in 50% of the DNA from his mother. The same mismatch PCR analysis with control DNA from 35 healthy individuals ruled out the possibility that the single base substitution (A186 to T) represents a common polymorphism. Inheritance of the second allelic mutation (G insertion) was verified by restriction enzyme analysis using BslI [CC(N)7GG] to digest PCR-amplified genomic DNA at the mutation site. PCR in combination with restriction enzyme analysis proved to be a powerful tool for verification of point mutations in the compound heterozygous CGD patient analyzed and may be used for prenatal diagnosis in this family.

Alleles↗

The plasma concentration of soluble Fc-gamma RIII is related to production of neutrophils.

Fc gamma RIII (the CD16-antigen), a low-affinity receptor for IgG, is expressed by neutrophils, natural killer lymphocytes and macrophages. A soluble form of Fc gamma RIII has been identified in human plasma. This soluble form of Fc gamma RIII (sFc gamma RIII) originates from release by neutrophils. In the present study we show by transfusions of plasma that contains sFc gamma RIII of one allotype (NA1-Fc gamma RIII) in recipients homozygous for the other allotype (NA2-Fc gamma RIII) that the clearance of sFc gamma RIII is about 0.7 ml/min. Because the concentration of sFc gamma RIII was found to be constant in a small cohort of donors followed for about 1.5 years, the half-life of NA1-sFc gamma RIII is about 1.8 d, assuming a one-compartment model. The plasma concentration of sFc gamma RIII depended mainly on the production of neutrophils in the bone marrow, and was not influenced by shifts of neutrophils from one pool to another (storage, marginating or circulating pool). Because Fc gamma RIII is only expressed on mature neutrophils, this implies that the concentration of sFc gamma RIII depends on production of mature neutrophils.

Acquired Immunodeficiency Syndrome↗

The genetic basis of chronic granulomatous disease.

Chronic granulomatous disease is a serious clinical entity. The disease is caused by the failure of NADPH oxidase in phagocytic leukocytes to generate superoxide, needed for the killing of micro-organisms. The patients need careful management aimed at prevention and aggressive treatment of infections. CGD is a heterogeneous syndrome, both clinically and genetically. This disease is caused by a diversity of mutations, and multiple genes are affected. In fact, in the A22 and X91 subtypes of CGD, in which the alpha subunit and the beta subunit of cytochrome b558 are affected, respectively, the mutations are virtually unique for each CGD family tested. The results of these studies provide a better understanding of the mechanism of action of the various components of the superoxide-generating enzyme. Although treatment of CGD patients has improved considerably over the past 30 years, death caused by overwhelming infections is still a serious threat. Prenatal diagnosis now provides the relatives of a CGD patient with the possibility to choose for first-trimester abortion of an affected fetus. Moreover, genetic correction of the disease is now a goal within reach.

Female↗